handbags-at-dawn

In British slang a fight where the protagonists are unable or unwilling to seriously hurt each other is commonly referred to as a handbag fight, in reference to the way girls fight by hitting each other with their handbags. Handbags at dawn is therefore a combination of the above with an allusion to 'pistols at dawn' style dueling to describe a conflict brought about by a perceived slight or offense to one's honour but which is nevertheless unlikely to result in any serious injury.